Bipolar electrosurgical scissors

ABSTRACT

Bipolar electrosurgical scissors are disclosed having a pair of blades joined for relative movement in a scissor-like action between open and closed positions. The blades comprise a tissue contacting surface and first and second spaced apart electrodes extending along the surface. Current flow between the first and second electrodes of each blade and between each blade to promote hemostasis in tissue contacting the surface.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of application Ser. No.08/399,421, now U.S. Pat. No. 6,179,837 filed Mar. 7, 1995.

BACKGROUND OF THE INVENTION

The present invention relates generally to electrosurgical scissors, andmore particularly, to bipolar electrosurgical scissors to assist inhemostasis of tissue as it is cut by the scissors.

It is common in many surgical procedures to use surgical scissors forcutting tissue that is vascularized, i.e., contains blood vessels. Theresultant bleeding that occurs is not only of concern from thestandpoint of blood loss, but the blood may also obscure the surgicalfield or site. Controlling such bleeding has, in the past, requiredsignificant time and attention of the surgeon during many surgicalprocedures.

In recent years, efforts have been devoted to developing scissors thatuse radiofrequency (“RF”) energy in a manner such that the tissue isheated as it is cut, to promote immediate hemostasis. Early efforts atsuch electrosurgical scissors used monopolar RF power, where thescissors constituted one electrode, and the patient rested on the otherelectrode, which was typically in the form of a conductive mat, tocomplete the circuit. Current flowed generally through the patientbetween the electrodes due to a voltage applied across the electrodes byan RF power supply.

Monopolar applications, however, had certain drawbacks. Inadvertentcontact between the scissors and other tissue could result in unwantedtissue damage. In addition, the flow of current through the body of thepatient could take uncertain or unpredictable paths with potentialunwanted injury to other tissue.

More recently, efforts have been made to develop bipolar electrosurgicalscissors to overcome the drawbacks with monopolar scissors.Specifically, efforts have been made to develop scissors in which oneblade includes one electrode and the other blade includes the otherelectrode, so that current flows between the blades as they cut thedesired tissue.

Example of recent efforts to develop bipolar scissors are found in U.S.Pat. Nos. 5,324,289 and 5,330,471. These patents disclose bipolarscissors in which one blade of the scissors has one electrode, and theother blade of the scissors has the other electrode, so that currentflows between the blades as they come into proximity during cutting.Various embodiments of bipolar scissors are disclosed in these patents,but typically a layer of insulating material is provided on at least oneshearing surface of one of the blades, and the hinge pin or fastenerwhich pivotally connects the blades is electrically insulated, so thatthe electrically active parts of the scissor blades do not contact eachother during operation of the instrument. With the construction as shownin these patents, the electrical current flows between the blades at apoint just forward of where the shearing surfaces actually touch. Thecurrent flow between the blades causes a heating of the tissue andpromotes local coagulation and hemostasis during the cutting procedure.

In U.S. Pat. No. 5,352,222, bipolar scissors are shown in which eachblade of the scissors is a laminated assembly of a metal shearingsurface, a metal blade support and intermediate layer of insulatingmaterial. The blade support of one blade acts as one electrode, and theblade support of the other blade acts as the other electrode, so thatelectrical energy flows between the blade supports as the blades closeon the tissue being cut. A short circuit between the shearing surface isprevented by reason of the insulating layer between the metal shearingsurface and the blade support. This scissor construction is purported tobe more economical to manufacture than the blade structure disclosed inU.S. Pat. Nos. 5,324,289 and 5,330,471. However, because the shearingsurface is a separate piece, bonded to the blade support, a particularlyhigh strength and high precision epoxy bonding process is required inthe '222 patent so that the shearing surface remains attached to theblade support despite the shearing forces exerted upon it duringrepeated cutting.

What the above patents have in common, is that each blade forms one ofthe electrodes attached to a bipolar RF energy source, so that the onlycurrent that flows is between the blades as they close. Although thebipolar scissors described in the above-identified patents are believedto be an advance over the earlier monopolar scissors, they typicallyrequired the electrically active parts of the blades to be insulatedfrom one another, which tends to complicate the design and materials ofthe blade actuating mechanism. Accordingly, development work continuesto provide bipolar scissors which are easy to use, more economic tomake, versatile and/or which are effective in promoting hemostasisduring cutting of various tissues, particularly including tissues thatare highly vascularized.

SUMMARY OF INVENTION

In accordance with the present invention, tissue cutting apparatus, suchas scissors, may be provided in which each cutting blade itself includestwo electrodes for connection to a bipolar RF energy power supply. Morespecifically, the tissue cutting apparatus of the present inventioncomprises a pair of blades joined for relative movement in ascissor-like action between open and closed positions. Each of theblades has a tissue contacting surface for contacting the tissuetherebetween as the blades close during the cutting action. The tissuecontacting surface of at least one and preferably both blades includesfirst and second spaced-apart electrodes which extend along the tissuecontacting surface and are connectable to a voltage source, such as ahigh frequency bipolar RF power supply, for applying a voltage betweenthe electrodes. As a result, current flows between the first and secondelectrodes of the blade to promote hemostasis in the tissue as the bladeis moved into contact with tissue, such as during the cutting action.

In accordance with other aspects of the present invention, the firstelectrode of each of the blades may also define a shearing surface and acutting edge of the blade. As in typical surgical scissors, the shearingsurfaces of the blades are in a face-to-face relationship, but inaccordance with the preferred aspects of the present invention, thefirst electrodes of each blade are of like polarity, so that there is noshort circuiting between the shearing surfaces of the blades. Becausethe contacting shearing surfaces are of like polarity, there is no needto insulate the blades from one another, and a less complicated and lessexpensive scissor construction is required than in the prior patentsdiscussed above. In accordance with this aspect of the presentinvention, the scissor shaft, which extends between the blades and anactuator handle, may itself be a conductor for connecting the firstelectrode of each blade to one terminal of a voltage source, and asingle insulated conductor extending along the shaft may be used toconnect the second electrode of each blade to the other terminal of thevoltage source. Further, where the first electrode defines the cuttingedge and shearing surface and also serves as the main structural elementof each blade, relatively little force is exerted on the secondelectrode during cutting. As a result, a special high strength or highprecision bonding process between the first and second electrodes isunnecessary, and less expensive bonding techniques should suffice.

In the above-described embodiment, the first and second electrodespreferably extend along a tissue contacting edge of the scissors, whichis in proximity to the cutting edge. Accordingly, the current flowbetween the first and second electrodes serves to promote hemostasis inclose proximity to the cut line, as the scissors are closed in a cuttingaction.

In accordance with another feature of the present invention, the firstand second electrodes of each blade are located so that current not onlyflows between the first and second electrodes of each blade, but alsobetween the first electrode of one blade and the second electrode of theother blade as the blades are brought into proximity during cutting. Theflow of current between electrodes of different blades and electrodes ofthe same blade enhances coagulation and hemostasis during the cuttingaction.

In accordance with another aspect of the present invention, the scissorsembodying the present invention may be used to promote coagulationduring a blunt dissection or similar procedure, where the opening actionof the scissors is used to contact or spread tissue. In this embodiment,each scissor blade has first and second spaced electrodes that extendalong the rearward edge of the blades to contact tissue and promotecoagulation as the blades are opened to spread or open tissue.

These and the many other features of the present invention, are setforth in the following detailed description of the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of electrosurgical scissors embodying thepresent invention.

FIG. 2 is a cross-sectional view of the distal end of theelectrosurgical scissors of FIG. 1, depicting one means for attachingand moving the blades between open and closed positions, with the bladesshown in an open position.

FIG. 3 is a longitudinal cross-sectional view of the distal end of theelectrosurgical scissors of FIG. 2, taken along line 3—3 of FIG. 2, withthe blades shown in a closed position.

FIGS. 4a-4 c are vertical cross-sectional views of one embodiment ofscissor blades employing the present invention, taken along line 4—4 ofFIG. 3, and showing the positions of the blades as they move from anopen position in FIG. 4a in contact with the tissue to be cut, to anintermediate position in FIG. 4b just after the tissue is cut, and to afully closed position in FIG. 4c.

FIGS. 5a-5 c are vertical cross-sectional views of another embodiment ofscissor blades employing the present invention, showing the positions ofthe blades as they move from an open position in FIG. 5a in contact withthe tissue to be cut, to an intermediate position in FIG. 5b just afterthe tissue is cut, and to a fully closed position in FIG. 5c.

FIGS. 6a-6 c are vertical cross-sectional views of a further embodimentof scissor blades employing the present invention, showing the positionsof the blades as they move from an open position in FIG. 6a in contactwith the tissue to be cut, to an intermediate position in FIG. 6b justafter the tissue is cut, and to a fully closed position in FIG. 6c.

FIGS. 7a-7 c are vertical cross-sectional views of a further embodimentof scissor blades employing the present invention, showing the positionsof the blades as they move from an open position in FIG. 7a in contactwith the tissue to be cut, to an intermediate position in FIG. 7b justafter the tissue is cut, and to a fully closed position in FIG. 7c.

FIG. 8 is a vertical cross-sectional view of one of the scissor bladesof FIG. 6, showing how a single blade may be used to promote hemostasisin tissue.

FIGS. 9a-9 c are vertical cross-sectional views of the scissor blades ofFIG. 5 showing the positions of the blades as they move from a closedposition in FIG. 9a, to an intermediate position in FIG. 9b, to an openposition in FIG. 9c, during a blunt dissection procedure.

FIG. 10 is a perspective view of an alternate embodiment ofelectrosurgical scissors embodying the present invention.

FIG. 11 is an exploded perspective view of the distal end of theelectrosurgical scissors of FIG. 10 showing the blade members andassociated structure.

FIG. 12 is an exploded perspective view of the proximal end of theelectrosurgical scissors of FIG. 10 showing the handle and associatedstructure.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, the present invention is generally embodied inelectrosurgical scissors, generally at 10, having a pair of scissorblades 12 joined for pivotal movement between open and closed positions.The present invention is not limited to any particular type or style ofsurgical scissors, and may be used in essentially any scissors that hasa pair of movable blades. The particular scissors 10 shown in FIG. 1 isthe type of scissors typically used in so-called minimally invasive orendoscopic surgery, where the scissor blades are inserted into the bodycavity of a patient through a small diameter trocar.

In the scissors 10, the scissor blades are located at the distal of anelongated tubular shaft 14. As shown in FIGS. 2 and 3, the blades 12 arepivotally attached by pivot pin 16, which also attaches the blades tothe distal end of shaft 14. A pair of linkages 18 connect the proximalends of the blades to an actuator rod 20 that extends through the shaft.Axial movement of the actuator rod, which is controlled by handle 22(FIG. 1) in a standard and well-known fashion, closes or opens theblades.

Alternatively, the proximal ends of the blades 12 may be slotted and theactuator rod 20 connected to a pin that slides within the slots, so thataxial movement of the actuator rod opens and closes the blades. Examplesof scissors employing a similar but somewhat more complicated structurethan necessary in the present invention are described in U.S. Pat. Nos.5,330,471 and 5,352,222, which are incorporated by reference herein.

In accordance with the present invention, as shown in FIG. 3, and inFIGS. 4-7, at least one blade, and preferably each blade of the scissorsincludes an inner conductive blade element 24 which defines a firstelectrode, an intermediate layer of insulative material 26 and an outerconductive blade element 28 which defines a second electrode. The innerblade element 24 includes a distal curved (or straight if desired) bladesegment 30, which extends generally from pivot pin 16, and a proximalmounting segment 32 that is typically received within the end of shaft14 and receives pivot pin 16 and linkages 18. Referring to FIG. 4a, eachblade has a cutting edge 34, a shearing surface 36 and a tissue contactsurface or edge 38 that extends along the cutting edge and contacts thetissue 40 as the blades close.

The inner blade element 24 is preferably metal, such as stainless steel,or other suitable material that is of high strength and will hold asharp cutting edge for repeated use. As best seen in FIGS. 4-7, theinside surface of the inner blade element 24 forms the cutting edge 34and shearing surface 36 of each blade. A forward surface 42 of the innerblade element extends along the cutting edge and the tissue contactsurface for substantially the entire length of the blade segment 30.

Insulative material 26, separates the inner blade element 24 from theouter blade element 28. The insulative material may be made any suitablematerial that has sufficient resistance to electrically insulate theinner and outer blade elements. Preferably, the insulative material 26also has sufficient bonding strength for bonding together the inner andouter blade elements. Because the outer blade element 28 does notinclude the shearing surface or cutting edge, the forces exerted on theouter blade element are limited, and the bond does not have to be asstrong, for example, as employed in U.S. Pat. No. 5,352,222. It isbelieved that a relatively thin layer or film of insulation, such as thethickness of ordinary electrical tape, will provide sufficientinsulation between the inner and outer blade elements. The spacingbetween inner and outer blade elements at the tissue contact surface ispreferably between about 0.002 and 0.050 inches. Ordinary adhesives ormaterials that are suitable for bonding to metal in medical applicationsshould suffice for bonding the inner and outer blade elements together.Alternatively, epoxy material, such as AF125 by 3M Company, as describedin detail in U.S. Pat. No. 5,352,222, may be used to provide theinsulative layer.

Outer blade element 28 is preferably a thin metal plate or strip, suchas stainless steel or aluminum. Forward edge 44 of outer blade element28 extends along the tissue contact surface 38, generally parallel toand spaced from the forward surface 42 of the inner blade element 24. Asshown in longitudinal cross-section in FIG. 3, the insulating material26 and outer blade element 28 preferably extend along the entire lengthof blade segment 30, including around the distal-most end of the bladesegment.

The scissors of the present invention are preferably intended forconnection to a voltage source, such as to the bipolar terminals of acommercially available bipolar RF energy generator. The bipolar RFgenerator may be connected to the scissors of the present invention atconnectors 46 and 48 located near handle 22. Connector 46 is attached toan insulated conductor 50 that extends through shaft 14 and is connectedat the distal end to each of the outer blade elements 28 of each blade.The other connector 48 is in electrical contact with the actuator rod 20and shaft 14 which, in turn, are in electrical contact with the innerblade elements 24 of each blade via linkage 18 and pivot pin 16,respectively. Accordingly, the inner blade elements of each blade areattached to the same terminal of the voltage source and therefore havethe same polarity. A standard insulating material such as plastic shrinktubing acts as a covering 45 along the outside surface of shaft 14, andprotects surrounding tissue by preventing inadvertent conduction ofelectricity to or from the surface of the shaft. Alternatively, theshaft could be made entirely of insulative material, and electricalcommunication to the outer blade elements could be solely through theactuator rod, or vice versa.

FIGS. 4-7 show various possible blade configurations, in cross-section,as the blades close on tissue to be severed. Referring first to FIG. 4,FIG. 4a depicts the blades as they are closed and when they first comein contact the tissue 40 to be severed. Each blade has a shearingsurface 36 and cutting edge 34. Each blade also includes an inside orforward tissue contacting edge surface 38. The inner blade element 24forms the cutting edge and shearing surface of each blade. The innerblade also includes the forward edge or surface 42 that extends alongthe cutting edge for essentially the entire cutting length of the blade.The outer surface and back edge of the inner blade element are coveredby insulative material 26. The insulative material 26 also extendsbeyond the back edge of inner blade element 24 to form an overhanginglip 52 of insulative material. This overhanging lip has a widthapproximately the same as or slightly greater than the width of theforward edge 42 of the inner blade element.

Outer blade element 28 extends along the tissue contacting edge surface38 of the blade for substantially the entire length of the blade segment30, and, as seen in cross-section, overlies only a portion of theoutside surface of the inner blade element 24.

As shown by the arrows in FIG. 4a, when the tissue contacting edge orsurface 38 of each blade comes into contact with the tissue 40 to becut, current is believed to flow through the tissue between the innerblade element 24 and the outer blade element 28 of each blade, and asthe blades come into proximity with each other, current flows throughthe tissue between the outer blade element 28 and inner blade element 24of opposite blades. The current flow at the initial point of contactingthe tissue is believed to be substantially between the inner and outerblade elements of the same blade along the tissue contacting edge. Asthe blades begin to cut the tissue and the distance between the bladesdecreases, the current flow between opposite electrodes of oppositeblades increases.

FIG. 4b shows the blades in a position where the tissue has beensevered, and the blades are not fully closed. At that position, it isunderstood that current flows substantially between the inner and outerblade elements of the same blade along the tissue contacting edge orsurface 38, and may also flow between the outer blade element 28 and theshearing surface 36 of the inner blade element 24 of the other blade.The extent of current flow through the tissue in this situation may varydepending on the tissue type, position, thickness, and the extent towhich the tissue is under tension.

FIG. 4c shows the blades in a fully closed position. At that position,the overhanging lip 52 of insulative material covers the forward edge 42of the inner blade element 24 of the facing blade, essentially fullyenclosing and insulating the inner blade elements 24 from tissuecontact, and preventing current flow therethrough.

FIGS. 5a-5 c show an alternative embodiment of the present invention inwhich each of the blades similarly has a cutting edge 34, shearingsurface 36, and tissue contacting edge or surface 38 for contactingtissue as the blades close. In addition, in this embodiment each of theblades includes a rearward edge or surface 54, which is displaced fromor opposite the tissue contacting edge or surface 38, and which may beused for cauterizing tissue in those situations where it is desirable tocauterize tissue with the rearward surfaces of the blades.

More specifically, as shown in FIG. 5a, each blade includes the innerblade element 24, insulative material 26 over only the outside surfaceof the inner blade element, and outer blade element 28 which fullyoverlies the outside surface of the inner blade element. With thisconstruction, as the tissue contacting edge of each blade comes intocontact with tissue 40 for cutting, current is understood to flowbetween the surfaces 42 and 44 of the inner and outer elements of thesame blade, and between the inner blade surface 42 and the outer bladesurface 44 of opposite blades. As the blades are moved to a closedposition, as shown in FIG. 5b, current is believed to flow between theouter blade surface 44 and the inner blade surface 42 of the same bladeand between the inner blade element and outer blade element of theopposite blades. When the blades are fully closed, as shown in FIG. 5c,the forward and rearward surfaces 38 and 54 of the inner and outerelectrodes of each blade are exposed, and current may continue to flowbetween the electrodes of each blade, when they are in contact withtissue.

The rearward edge of each blade in FIG. 5 has the same construction asthe inside or forward edge of the blade, with tissue contacting surfaces42′ and 44′ extending along the rearward surface 54, and therefore maybe used for assisting in severing and promoting hemostasis of tissuethat is contacted by the outside of the blades in a procedure such asblunt dissection. FIGS. 9a-9 c depict use of the scissors of FIG. 5 in aprocedure such as a blunt dissection. A blunt dissection as depicted inFIG. 9 is where the scissors are inserted into the tissue in a closed orsemiclosed position, and then opened to spread the tissue. Such aspreading action may result in bleeding from blood vessels rupturedduring the procedure. In accordance with the present invention, thescissors of FIG. 5 may be used not only for promoting hemostasis duringnormal cutting but for promoting hemostasis during blunt dissection orthe like.

FIG. 9a shows the scissor blades of FIG. 5 inserted into tissue 40 in aclosed or near closed position. In this position, current flows throughthe tissue between surfaces 42 and 44 of the same blade at the insidetissue contacting surface and between surfaces 42′ and 44′ of the sameblade at the rearward tissue contact surfaces. As the blades are movedto an intermediate position, the inside surfaces are no longer in closetissue contact and current flow between the inner and outer bladeelements reduces or ceases. Current continues to flow through the tissuein contact with surfaces 42′ and 44′, promoting hemostasis in the tissueas the scissors spread. This current flow and hemostasis continues asthe scissors fully open, as shown in FIG. 9c.

FIG. 6 shows another embodiment of the present invention, in which theinner blade element 24 is of essentially the same shape as that shown inFIG. 4, with the insulative layer 26 covering the same portion of theinner blade element as also shown in FIG. 4. In FIG. 6, however, theouter blade element 28 extends fully around the inner blade element tothe same extent that the insulative material 26 extends around thematerial. The current flow between inner and outer elements of theblades in FIG. 6 is essentially the same as that described for FIG. 4.Also, similarly, when the blades are fully closed the inner bladeelements 24 are essentially fully enclosed by the insulative material 26and current flow between the inner and outer blade elements iseffectively prevented. In this configuration, the outer electrode couldbe used as a monopolar electrode when the scissors are closed.

FIGS. 7a-7 c show yet another embodiment of the present inventionsimilar to that of FIG. 6. In this embodiment, however, the inner bladeelement 24 tapers to a point at the tissue contacting edge or surface.In this embodiment, it is believed that the maximum amount of currentflow will occur between the outer blade element of one blade and theinner blade element of the other blade as the blades sever the tissue.It should be noted that the wider the inner blade element surface 42 is,the more current will flow between electrodes (inner and outer elements)of the same blade, and the narrower the surface 42, the more currentwill flow between electrodes (inner and outer elements) of oppositeblades. If the surface 42 width exceeds the typical current path lengthfor bipolar energy (i.e., is greater than about 0.050 inches in width)then most of the current flow will occur between electrodes (inner andouter elements) of the same blade.

Finally, FIG. 8 depicts how the forward or tissue contact surface of asingle blade embodying the present invention may be used to promotehemostasis independent of the tissue being severed.

Turning to FIGS. 10-12, there is seen a further embodiment of anendoscopic bipolar electrosurgical scissors in accordance with thepresent invention generally designated as 100. Like the embodimentdescribed above, the scissors 100 comprises two inner conductive cuttingblades 102, 104, each having an insulating member 106, 108,respectively, that is bonded to its blade member with a suitableadhesive. The insulating members 106, 108 each carry an outer electrode110, 112, respectively.

The blades 102, 104, are joined together for pivotal movement to atwo-part clevis 114 a, 114 b that is attached to the distal end of aconductive flexible tube member 116, the proximal end of which issecured to a handle 118 comprising two-parts 118 a, 118 b forcontrolling the opening, closing and electrical activation of theblades. The flexible tube 116 encases a flexible, helically-wound andcoated wire tube 117 that is substantially coextensive with the tube116. An insulative shrink fit tube 119 covers the tube 116 and theproximal portion of the blades 102, 104. In keeping with one aspect ofthe invention, improved means are provided for coupling the two outerelectrodes 110, 112 to a voltage source of a first polarity and the twoinner conductive cutting blades 102, 104 to a voltage source of a secondpolarity opposite to the first.

To conductively connect the outer electrodes 110, 112 to a voltagesource of a first polarity, the handle includes an internal lug 120 inits proximal end that supports a first conductive contact 122. The lug120 is maintained in position in the handle by means of a shim 123. Theconductive contact 122 includes two arms 124 that are crimped to aconductive wire 126 that extends from the proximal end to the distal endof the handle. The distal end of the wire 126 is conductively connectedto the proximal end of the flexible tube member 116 by means of aconductive connector 128 that is crimped to the wire 126 on one end andto a rigid member 130 on the other end that is press-fit into theproximal end of the conductive flexible tube member 116. The distal endof the flexible tube 116 has a conductive coupler 132 that secures theclevis 114 a, 114 b to the tube 116 by a crimp fit. An elongatedconductive contact 134 is attached to the outer portion of each clevishalf 114 a, 114 b.

The distal end of each conductive contact 134 extends slightly beyondthe end of the clevis half to which it is attached so that it is infrictional or wiping contact with its associated outer electrodethroughout the range of motion of the blade. Thus, when voltage of afirst polarity is applied to the handle, it travels from the contact 122through the wire 126 and connector 128 to the conductive tube 116. Fromthe conductive tube 116, the voltage travels through the proximal end ofthe coupler 132, which conducts the voltage to the two contacts 134which are conductively in contact with the inside surface of the couplerand, in turn, conduct the voltage to the outer electrodes 110, 112.

To conductively connect the inner conductive cutting blades 102, 104 toa voltage of a second polarity opposite to that applied to the outerelectrodes 110, 112, the internal lug 120 in the handle supports asecond conductive contact 136. The conductive contact 136 includes twoarms 138 that are crimped to a second conductive wire 140 that extendsfrom the proximal end of the handle to a pivotable thumb lever 142,which is discussed in greater detail below. The distal end of the wire140 is secured to the thumb lever 142 by means of a conductive connector144 that is crimped to the wire 140 on one end and to a conductiveconnector 146 on the other end that is press fit into a pivot connector148 mounted to the lever 142. The connector 146 attaches to aconductive, flexible push rod 150, which is covered with an insulativeshrink tube 151, that extends from the handle through the coated wiretube 117 to the blades 102, 104. A conductive clevis 152 is soldered tothe distal end of the push rod 150 and supports a conductive pin 154that is captured within obliquely-oriented slots 156 in the proximalportions of the inner conductive blades 102, 104. Thus, when a voltageof a second polarity is applied to the handle, it travels from thecontact 136 through the wire 140, connector 144 and connector 146 to thelever 142. In the lever, the voltage travels from the connector 146through the push rod 150 to the clevis 152 and pin 154, which contactsthe inner conductive blades 102, 104.

To pivotally mount the blades 102, 104 to the clevis 114 a, 114 b andimpart pivotal movement to the blades 102, 104, each blade includes anaperture 158 that receives an eyelet 160. The eyelet 160 extends betweenand interior of the clevis halves 114 a, 114 b. A rivet 162 whose shaftis received inside an insulating tube 164 extends between the exteriorof the clevis halves 114 a, 114 b, thus pivotally securing the blademembers 102, 104 together to the clevis halves 114 a, 114 b. The obliqueslots 156 in the proximal ends of the blades create, in effect, leverarms to open and close the blades as the push rod pin 154 is moved backand forth.

Longitudinal motion is imparted to the push rod 150 by means of the backand forth movement of the thumb lever 142, the proximal end of the pushrod 150 being secured to the pivot connector 148. The pivot connector148 is, in turn, rotatably secured to an aperture in the lever 142 by aset screw 168. Thus, translational movement of the push rod 150 isprovided by pivotal movement of the lever 142, with the pivot connector148 rotating so that any sharing of force applied to the push rod 150 isminimized.

Although various alternative constructions for the electrosurgicalscissors of the present invention are depicted, the present invention isnot limited to these particular versions, and it is anticipated thatother configurations may be used embodying the present invention whichdepart from the particular construction shown.

What is claimed:
 1. In a bipolar electrosurgical scissors having a pairof blades joined together for relative movement in a scissors-likeaction between open and closed positions, with a handle operativelyconnected to the blades for effecting relative movement of the blades,each of the blades comprising an inner electrode and an outer electrodewhich are spaced-apart by an insulating member, the outer electrode ofeach blade being adapted to be connected to one terminal of a voltagesource having a pair of terminals of opposite polarity, and the innerelectrode of each blade being adapted to be connected to the otherterminal of the voltage source so that the outer electrodes are of afirst polarity opposite to that of the inner electrodes, the improvementcomprising means for coupling the outer electrodes to the voltage sourceof the first polarity including: a contact for connecting the handle tothe voltage source of a first polarity; an elongated conductive tubehaving a proximal end connected to the handle and a distal end thatreceives the pair of blades; a conductor within the handle connectingthe contact to the tube; and a pair of elongated contacts, each havingproximal and distal ends, the proximal ends extending into the distalend of the conductive tube and making electrical contact with the insidesurface of the tube and the distal end of each elongated contact beingheld in frictional engagement against one of the outer electrodes of theblades throughout the range of movement of the blades between open andclosed positions.
 2. In a bipolar electrosurgical scissors having a pairof blades joined together for relative movement in a scissors-likeaction between open and closed positions, with a handle operativelyconnected to the blades for effecting relative movement of the blades,each of the blades comprising an inner electrode and an outer electrodewhich are spaced-apart by an insulating member, the outer electrode ofeach blade being adapted to be connected to a terminal of a voltagesource having a pair of terminals of opposite polarity, the improvementcomprising means for coupling at least one of the outer electrodes to avoltage source terminal, including: a contact for connecting the handleto the voltage source of a first polarity; an elongated conductive tubehaving a proximal end connected to the handle and a distal end thatreceives the pair of blades; a conductor within the handle connectingthe contact to the tube; and at least one elongated contact, theelongated contact having proximal and distal ends, the proximal endextending into the distal end of the conductive tube and makingelectrical contact with the inside surface of the tube and the distalend of the elongated contact being held in frictional engagement againstthe outer electrodes of one of the blades throughout the range ofmovement of such blade between open and closed positions.